Yellowtail damsels bullying four-stripe damsel

[mjs61290]

Hey all.

I recently decided to start a 40-gallon damsel tank. Damsels are by far my favorite fish due to their color, activity and hardiness. I'm sure some of you will agree!

I made my purchases yesterday. I picked up two yellowtails and a four-stripe damsel. My thinking was that the four-stripe was the more aggressive species, so I would get two of the yellowtails so they would feel more comfortable. The two yellowtails I bought were in the same tank together in the store and looked to be getting along great.

I came home, acclimated them and put them in the tank. They all hid for the first few hours, and later on when I entered the room, I noticed the four-stripe out and about. Then, I saw one of the yellowtails lunge out from a rock and nip him.

Today, it's more of the same. Anytime one of the yellowtails (it might just be one of them; can't really tell) sees the four-stripe, it chases him.

The yellowtails are eating, but the four-stripe isn't.

It seems odd that the normally more laid back yellowtails would bully the generally aggressive four-stripe, so that raises two questions on my end:

1.) Is it possible the yellowtails are a mated pair, hence the aggression? They get along just fine with one another.

2.) Would adding more damsels to spread out the aggression be a possible solution? Maybe picking up a blue damselfish and/or another four-stripe?

It doesn't seem like this is a matter of territory, as the yellowtails are attacking no matter when they see the four-stripe. So, rearranging the rockwork probably won't solve the issue here.

[Moort82]

I think it is partly settling in, with a get them before they get you mentality going on, and partly I believe it is territory. Damsels would defend a space bigger than your tank in nature. Also because its different it could be seen as the invader to their territory as they would be used to other yellow tails, living in a group, but would fiercely defend against other species. If you added another 4 stripe I think they would then have the advantage and your yellow tails would suffer. This way round is better as long as the four stripe is not getting major damage, as it should all settle down after a few days.
I'd just keep an eye, not add anything, and i'm sure when the 4 stripe has settled in it will give back what it gets plus more.

[mjs61290]

I think it is partly settling in, with a get them before they get you mentality going on, and partly I believe it is territory. Damsels would defend a space bigger than your tank in nature. Also because its different it could be seen as the invader to their territory as they would be used to other yellow tails, living in a group, but would fiercely defend against other species. If you added another 4 stripe I think they would then have the advantage and your yellow tails would suffer. This way round is better as long as the four stripe is not getting major damage, as it should all settle down after a few days.
I'd just keep an eye, not add anything, and i'm sure when the 4 stripe has settled in it will give back what it gets plus more.
Thanks a lot! I actually turned the lights out earlier today, and since I did that they have all been in their little hiding spots and I have not witnessed any more quarrels. Hopefully it stays this way.